stupid truing question (facing lugs/abutments)

[Jay Christopherson]

I watched someone truing a Remington action. As part of the process, they squared up the lug abutments (in the action) and then the backside of the lugs on the bolt. The mating surfaces as it were. They took off very little on each, just enough to get 100% cleanup.

The question I have though is: if you are removing material from both surfaces, aren't you creating a bigger *gap* between those two surfaces, no matter how little you remove? And isn't a bigger gap "bad"?

I should have asked the question then and there, but it didn't occur to me until later.

 

[Cigarcop]

You take off very little as to not screw up your camming....if you take too much off you would be well served to install another handle in the proper location.

To answer your original question if I'm reading it correctly...your not making a bigger gap between those two surfaces, (Action lugs and rear side of the bolt lugs) you infact making them have 100% contact. The gap your creating is between the bolt handle and the action itself screwing up the camming if too much is removed.

 

[Jay Christopherson]

Ok, I think I see. So the datum for the bolt being closed and engaged properly (i.e., no play) is set by the handle- if you take off too much metal on the rear of the bolt lugs and the action lugs, you are looking at moving the handle forward to take up the gap and correct the camming.

 

[Cigarcop]

Yes sir

 

[X Ring Accuracy]

Another way to say it is primary extraction. Typically, if you remove more than .006 to .008 total, primary extraction suffers. That extraction occurs at the rear of the action. Hence bolt handle needs re timing.

 

[Jay Christopherson]

Thanks guys, that makes sense now.